Willis Tower is a landmark skyscraper located in the heart of Chicago, Illinois. Formerly known as the Sears Tower, it once held the title of the tallest building in the world and remains one of the tallest structures globally. Its bold design and sky-high observation deck have made it a symbol of Chicago’s architectural legacy.
You can explore more iconic landmarks like this in our collection of historic American architecture.
The building is known for its bronze-tinted and black aluminum glass exterior.
Planning for the Willis Tower began as early as 1969. The tower was originally named the Sears Tower, after the retailer of the same name. At the name, Sears had a large number of employees in the Chicago area. In order to consolidate them in one place, the Sears Tower was conceived.
Skidmore, Owings & Merill were selected as the architects for the building. One of the key figures involved in the planning and construction of the Willis Tower was Fazlur Rahman Khan. Khan was the main structural engineer involved in the project. And he was instrumental in crafting a unique and defining outlook for the building.
The Willis Tower is among the first buildings to make use of ‘tubes’. It essentially comprises of 9 tubes, designed in a 3 x 3 matrix. The nine tubes rise concurrently up all the way to the 50th floor. The tube-like structures enabled Khan and SOM architects to ensure structural integrity of a building of exceptional height.
As the building rises up, the external tubes terminate and only the core tubes continue. From 90th to 180th floors, two tubes remain. This structure gives Willis Tower its iconic ascending shape.
The building has a total of 110 floors with 3 basement floors. It stands 442 meters of around 1450 feet tall. Together with the antennas installed at the top, the building’s height is 1729 feet. The building houses around 104 elevators.
One of the notable features of the Willis Tower is its observation deck, known as the Sky-deck. The deck is located on the 103rd floor. At a height of 1353 feet, it offers a stunning and sweeping view of the city. The structural design of the building allows it to sway in high wind conditions – and visitors can experience this extraordinary phenomenon at the observation deck.
More than 1.5 million people visit the Sky-deck every year. A stunning feature of the Sky-deck is the glass balcony. This all-glass structure allows visitors to stand on top of transparent glass and look down, getting a feeling of being in the air.
The Willis Tower is known for its incredible height, its Skydeck with The Ledge glass boxes, and its place as one of the tallest buildings in the world.
The Willis Tower stands at 1,450 feet (442 meters) to its roof and 1,730 feet (527 meters) including its antenna.
No, it was originally known as the Sears Tower when it was completed in 1973. The name changed to Willis Tower in 2009.
Yes, the Skydeck on the 103rd floor is open to visitors and features glass boxes that extend outside the building.
The Willis Tower is located at 233 South Wacker Drive in downtown Chicago, Illinois.
The Sears Tower: The History of Chicago’s Most Iconic Landmark Paperback – March 1, 2015
Sears Tower: A Building Book from the Chicago Architecture Foundation Hardcover – July 1, 2002